A standard press, used for instance to hold together two mold halves during an injection-molding operation, has a relatively massive frame, typically of C-shape. One of the mold halves is mounted on one arm of the frame and an actuator braced against the other arm of the frame can press the other mold half toward and away from the one mold half. As such machines can be used to exert enormous pressures (see "Druckgie.beta.maschine mit 2200t Schlie.beta.druck" by E. Brunhuber) it is not uncommon for the frame and mold halves or pressure plates carrying these halves to deform during a pressing operation.
As a result of this deformation the mold halves can deform and/or get canted or tipped. The result can be leakage out one side of the mold, excessive formation of flashing between the mold parts, or even damage to the machinery.
It has therefore been suggested in German patent documents 2,028,009 of Mnilk and 4,317,476 of Krell to provide a liquid-filled closed chamber between one of the mold parts and its support element. While such a system has some effectiveness in making pressure uniform over the surface of the mold, it cannot readily adapt to relatively tipped mold halves. In addition leakage is a problem under the extreme pressures used and such an arrangement must be cooled or insulated if it is to be used in a typical heated molding apparatus where temperatures are encountered that could vaporize the liquid.